Piezo electric crystal apparatus



Sept. 8, 1931. D. 1.. RYAN ET AL.

PIEZO ELECTRIC CRYSTAL APPARATUS Filed Dec. 22, 1928 rIllpllllllllIlllljllllllllllllilfllllIlllI QM Q afjiw @zma ATTORNEYPatented Sept. 8, 1931 UNITED STATES PATENT OFFICE DENNIS L. RYAN ANDALFRED CBOSSLEY, OF WASHINGTON, DISTRICT OF COLUMBIA,

ASSIGNORS TO WIRED RADIO, ING, OF NEW YORK, N. Y., A CORPORATION OFDELA- WARE PIEZO ELECTRIC CRYSTAL APPARATUS Application filed December22, 1928. Serial No. 327,935.

Our invention relates broadly to piezo electric crystal apparatus andmore particularly to a construction of holder for piezo electriccrystals. I

One of the objects of our invention is to provide a construction ofpiezo electric crystal holder which is particularly adapted forsustaining oscillations within a frequency band of 150 to 6500kilocycles.

Another object of our invention is to provide a construction of piezoelectric crystal holder having means for centering a. piezo ard electrontube socket, where the holder has a rugged construction and is capableof shipment without breakage of the piezo electric crystal carriedwithin the holder, 7

Other and further objects of our invention reside in the construction ofpiezo electric crystal holder as set forth in the specificationhereinafter following by reference. to

the accompanying drawings in which:

Figure 1 is a plan view ofthe piezo electric crystal holder of ourinvention; Fig. 2 is a side elevation of our piezo electric crystalholder; Fig. 3 is a longitudinal cross-sectional view taken through thepiezo electric crystal holder; and Fig. 4 is a lateral cross-sectionalview on line 44 of Fig. 3. e

Our invention is directed to the construction of a piezo electriccrystal apparatus of the general class set forth in Letters Patent No.1,572,773. to Alfred Crossley, dated February 10, 1926, and in LettersPatent to C. B. I

Mirick and Alfred Crossley, No. 1,683,093,

dated September 4, 1928. We have, however, considerably improved thestructure of the piezo electric crystal holder set forth in the abovepatent for improving the efliciency of operation of the piezo electriccrystal apparatus and insuring the protection of the piezo electriccrystal against damage in the course of shipment of the crystal to theplace of in;

stallation.

Our present construction of piezo electric crystal holder may be mountedin an electron tube socket and has proven highly satisfactory for usewith crystals which sustain oscil-,

lations within a frequency range from 150 to 6500 kilocycles. Thecrystal holder is extremely simple in its construction, has a lowmanufacturing cost and a high degree of ruggedness and may be readilyadjusted. The adjustable parts are all accurately tapped into metallicbushings avoiding the generation of minute particles which tend to bebroken off during adjustment when a metallic member is threaded into aninsulated body portion, as has heretofore been the practicein crystalholders, which particles tend to work their way under the crystal, thatis,between the surface of the crystal and the electrodes,

and stop the crystal from oscillating. We

provide an adjustable member which serves to locate the crystal adjacentone end of the easing while eliminating any effects of damping by reasonof the proximity of the adjustable guide with respect to the surface ofthe crystal.

Referring to the drawings in detail, reference character 1 designates aninsulated body structure upon which the parts of the piezo electriccrystal apparatus are mounted. A

threaded ring member 2 is positioned in one end of the cylindrical body1 to receive the threaded end plate 3 substantially in the form of aplug for closing the end of the casing. The end-plate 3 removable bygrasping the narrow peripheral edge 4. The inner surface of the endplate 3 provides a support for the piezo electric crystal element 6which has its lower surface resting in contact with the upper surface ofthe plate 3. The piezo electric crystal 6 may be in the form of a discor a parallelopiped. Convacuum tube SOQli-Gll'.

nection is made to the upper surface of the piezo electric crystal bymeans of a plate member 7 which rests upon the surface of the crystal.The opposite end of the insulated casing 1 is provided with; a: cutawayshoulder portion 8 to receivethe cylindrical portion 9 from whichproject pins 10 which serve as stops when the piezo electric crystalholder is inserted inthe standard bayonet portion 9, which mayconveniently be metallie, is substantially in the fornrof amend-caphaving a central annular shoulder portion V 11 thereon which is tapped"at 1'2" to receivethe threaded studinember 1, 1 which projects from therotatable plate or guide 15. The

plate 15'i'scut, away at itsunder. surface as tween the piezo electric.crystalirchamber and the upper portion iofthe holder, andeliminatereflection of sound, waves, fr,om the crystal. Wie have-ffoundthatwherethe reflection and dampingphenomena are not eliminated the V oscillationcharacteristics of the crystafwill ill,

be impaired. A, flexibleeonnection is taken from- 11h eplate 1 5vto theelectrodefif as representedlat 19. The end of'jt hje stud-14. isslotidasindicated at, 20 to. perm/nit the accurate a jus m ntofithapl'ate 1,5. withrespect to the pieZo electric crystal After thead'jusjtment lias'oncc be nfixed he,settiilgct iuscseleeted s, madepermanen qby rfil-liiigf he Well" 21 amu ditheheadf. thestud; 1'4 with.solder other molten metalgi'as epresented at 22.

v The top ofjthecasingis thenprotected fby a baklclitecover asshown at23 whichis-secured" to the cylinder portion 9'bymeansof the screw 24.Electrical connectionis made withtheepposi'tesurface ofthepiezo electriccrystal, element 6" throughthe lower surface cf'the endplate-B andthrough the projecting studslQwhich are at opposite potential'withrespect' to the end plate 3. The retaining m611ib811017pl2lt615i soconstructed that the piezorelectric crystal: 6 cannot. junipclear of theuppe g-electrode 7: because byscrewing do'wnqon the stud, 1 4::

a minute clearance is Thecylindrical obtained between the upperelectrode 7 and the shoulder or flange 17 This small clearance allowsfree vibration of the piezo electric crystal without restriction butpermits a minimum amount of play and practically keeps the crystal inthe same relative position and reduces the chance of breakage in transitto a minimum. The crystal may in this Way be protected when the holderis shipped to the place of installation after having been adjusted atthe place: of manufacture; 7

We have found the piezo; electric. crystal apparatus of our invention tobe highly efficient in its operation and practical in constructi'on andwhile we have described a specific embodiment of theinvention we desirethat it be understood that modifications maybeinade and-that nolimitations upon our invention are intended other than are imposedby thescope of the appended claims.

lVhat weclaim as new "and desire. to secure by, LettersPatent offthe.United States i'sas follows;

1 In piezo electrical crystal apparatus; in combination,. a. circulanmetallic base, plate provided with,circumferentialthreads; anannularinsulating body. structure,. a: tapped metallic ring secured to one;end. of said'ibody structure and" engaging; said threads of said baseplate, a centrally tapped metallic; cap securedctiostlie oppositeendofisaidbody structure, a piezoelectric: crystal supported uponsaidbase plate,,. an upperelectrod'e adjacent the, upper surfaceoffsaidcrystalp a restraining plate adjacent said. uppen electrode andprovided with. a. threaded central stud engaging sa'idl tapped portion:of said. cap, whereby the relative positions of said base 7 plate andsaid restraining plate may be controlled1by. screw thread adjustmentsinvolving only the bearing ofmetal-uponmetal.

2.- In piezoelectric, apparatus,.in combination,all1annular'insulatingbody structure of smooth bore a circular metallicbase plate provided. with. circumferential.threads,v at. tappedfmetallic ring secured to one end, of said'liody. structure andengagingsaidlthreads of saidibasefplate, ,a:c.entrally tappedfcapcarcried, by theopposite. rendlofj said body. structure, a, piezo electriccrystal supported upon saidlbaseplate an upper electrode adjacent the.upper. surface of. said, crystal, anda. re-

' strainingplate adj acentsaid' upper. electrode and. provided, with athreaded central? stud engaging saidtlireaded portion: of said cap. i.3.. n. piezo. electric crystalj apparatus-,-. in combinatiom. acircular. metallic, base, plate provided with. circumferential:threads,, an annular insulating bodyrstructure, a metallic ring securedto one end ofsaidebody structure and adapted to engage said-y threads ofsaid baseplate,-c a; centrally,- tapped metallic cap secured totheopposite end of said body structure, a; piezo electric crystal supporteduponsaid basesplatey an upper 'electrode-adnatures.

DENNIS L. RYAN. ALFRED CROSSLEY.

